Field of Invention
The present invention relates to a method of synthesizing ferrate, and more particularly to a method of producing ferrate composite pharmaceutical which is suitable for mass production and industrialization with high quality such that the application of ferrate can be fully realized.
Description of Related Arts
At present, there are three basic methods for synthesizing ferrate: (1) wet oxidation; (2) electrolysis; (3) high temperature peroxidation (dry). However, all these methods have a certain level of limitation in industrial production. The method of hypochlorite oxidation is mature, and the yield and purity is good. However, during the operation, the temperature is required to keep at near zero degrees Celsius, the operation is complicated and susceptible to introduction of other contaminants. The method of electrolysis is simple in operation while the raw materials consumption is low. However, the power consumption is high, the number of by-products is high, the number of influencing factors is high and the yield is low. The method of high temperature peroxidation has a higher yield and purity. However, a higher temperature is required, which results in the risk of explosion.
Since ferrate treatment results in multifunctional water purification effect such as oxidation, adsorption, co-precipitation, disinfection, sterilization and algae removal, it is an ideal water treatment agent for industrial wastewater and drinking water. At present, the limitations of large scale application and use of ferrate include high complexity of its synthetic methods, low yield, large commercial investment requirement, and high production cost.
In Russ J Inorg Chem, 34 (1989), pp. 1250-1253, Y. M. Kiselev et al. disclosed a method of preparing ferrate by heating iron oxide and sodium peroxide at 370° C. while introducing oxygen gas. This method is very difficult in operation and there is a danger of explosion. In “Preparation and purification of potassium ferrate(VI)” Chem Anal, 73 (1951), pp. 1379-1381, G. W. Thompson et al. disclosed a method of preparing ferrate by using alkaline sodium hypochlorite and ferric nitrate, and the ferrate product in solid state is precipitated by saturated potassium hydroxide. In this method, during the reaction, the temperature is controlled to not exceeding 20° C., and purification by organic substances such as benzene, ethanol and ethyl ether is required. In U.S. Pat. No. 5,746,994, the method of preparing ferrate by oxidizing ferric sulfate with monoperoxosulfate in the presence of a strong base is disclosed. This method requires an ice bath and the reaction temperature is required to be controlled below 0° C. In the PCT publication number WO2012/044358 A1, which is published on Aug. 7, 2013, Virende K. Sharma disclosed a method of preparing a ferrate solution by first obtaining a ferrate intermediate through heating ferric salts and sodium peroxide under 400˜650° C., through an electrochemical process, and/or through burning a mixture of iron salts and ethylene glycol then, after cooling, adding a halogen solution or introducing ozone to the ferrate intermediate. This method is very complicated, requires high temperature heating or high power input, which has a high power consumption. In the Canadian patent number CA2703708C, published on Jan. 31, 2012, Lee Edward Ciampi et al. disclosed an electrochemical synthetic process for producing ferrate continuously by utilizing a two-reaction chamber and two-electrode system. The efficiency of this method is affected by many factors which includes the electrode materials, composition of the electrolytes and current density while there exists the problem of electrode purification. In recent years, domestic scholars in our country are increasingly concerned about the application of ferrate in contaminant removal from drinking water. However, due to the lack of experience and reference of mature synthetic technology, the implementation of commercial production of ferrate is not realized.